A. Field of the Invention
This invention relates generally to filters for tobacco smoking devices, and particularly to the use of filter materials that are capable of trapping and removing deleterious chemical compounds, both polar and non-polar, from tobacco smoke.
B. Description of the Related Art
Tobacco smoke contains thousands of chemical compounds of various kinds from the combustion of tobacco. It is well known that many of these compounds are physiologically detrimental to habitual smokers. Recent studies further indicate that tobacco smoke can also harm nonsmokers. Thus, concern about the health hazards caused by tobacco smoke has grown steadily, prompting research for better ways of reducing the harmful effects of tobacco combustion.
Conventional methods for removing or reducing deleterious chemical components from the tobacco smoke include use of filters consisting of cellulose acetate fiber, activated carbon, or the like. These filters reduce the concentration of these harmful components in tobacco smoke to a certain extent, but their efficiency is still unsatisfactory. For example, these filters do not selectively adsorb ionic or polar compounds from the tobacco smoke, many of which are believed to be among the most highly deleterious to the body.
Two recent U.S. patents disclose use of silaceous materials to retain chemical compounds in the tobacco smoke. In U.S. Pat. No. 4,637,408, a multi-component filter, which is capable of removing nitric oxide from the smoke, contains a hydrophilic fumed colloidal silica. U.S. Pat. No. 4,744,374, on the other hand, describes a new family of compounds, namely, hydrophobic microporous crystalline tectosilicates. It is claimed that these compounds, which are free of hydroxyl groups, can be used in a cigarette or pipe filter to absorb carbon monoxide.